1. Field of the Invention
The present invention generally relates to aiming sights for use with firearms and, more particularly, to an aiming sight having a fixed light emitting diode (LED) array and a rotatable collimator which function together to change angular position of an aiming dot such that the aiming dot has parallax-free performance over a relatively large elevation angle adjustment range.
2. Background Art
Certain firearms launch relatively low-velocity projectiles such as grenades, air burst ammunition, and non-lethal rubber bullets. Low-velocity projectile firearms require aiming sights having a wide elevation angle adjustment range because the amount of projectile drop increases significantly with distance from the firearms to targets. Traditionally, aiming sights used with such firearms have been leaf sights. A leaf sight is an iron sight with a tall front sight. Leaf sights are limited to providing coarse aiming.
Low-velocity projectile firearms are becoming more accurate and consistent. Compact laser range finders are now available to provide precise data on target range. As such, a complete and precise fire control system for a firearm is required to take advantage of firearm accurateness and the available precise target range data.
A fire control system for a firearm generally includes a laser range finder (with a tilt sensor), a ballistic computer, and an aiming sight. The laser range finder with its tilt sensor determines the effective target range. The effective target range takes into account the elevation or depression angle of the target relative to the weapon. The ballistic computer uses the computed effective target range to determine the proper elevation angle for the firearm to engage the target. The aim point of the sight is then moved down by the same angle. By putting the aim point on the target, the firearm is tilted up to the proper elevation angle. The elevation angle adjustment of the aiming dot has to be accomplished quickly so that the target can be engaged soon after the target range has been determined.
For weapons that launch low-velocity projectiles, the elevation angle adjustment range required of the aiming sight may be as large as 30°. The field of view of an aiming sight having a magnified scope is relatively very small. As such, to cover the elevation angle adjustment range the entire magnified aiming sight is usually rotated in order to aim the aiming dot at the target.
The field of view of an aiming sight having a 1× magnification such as a reflex or red-dot sight is larger. However, the collimator optics of a 1× sight maintains proper collimation and hence parallax-free performance of an aiming dot only over a small angular range (typically within 1°). Outside of this small angular range, off-axis aberration of the reflective collimator will introduce significant parallax aiming error. As such, once again, to cover the elevation angle adjustment range the entire 1× aiming sight has to be rotated in order to aim the aiming dot at the target.
Rotating an aiming sight in its entirety is typically done mechanically using a small motor. The rotation of an entire aiming sight is relatively slow because of the amount of mass to be rotated which could include control electronics and batteries. Moreover, an exposed external aiming sight rotation mechanism is prone to jamming by dust and mud and is prone to environmental conditions such as salt fog.